Strange problem - need unused variable to make (Blink like) sketch run

I am sure, I posted the right thing. I tryit more times and did more variants of it, this one is the simplest, which does something visible.

I also tried avr-objdump -DCfhlSwz Ugh.cpp.elf >Ugh.cpp.asm and found, that there is difference, as the working version have .data segment and does incrementing the led

    led++;
 104:   80 91 00 01     lds     r24, 0x0100
 108:   90 91 01 01     lds     r25, 0x0101
 10c:   01 96           adiw    r24, 0x01       ; 1
 10e:   90 93 01 01     sts     0x0101, r25
 112:   80 93 00 01     sts     0x0100, r24